How to get over a bug in 24 hours?

ok so for the past few days, I've been feeling very tired and weak, and my stomach was bugging me a little. I dont feel like eating, tho eating makes me feel a little better, but then later, my stomach starts feeling weird again. I havent thrown up, im...

mostly just really tired. I cant stand for longer than 5 minutes.

the problem is, the two biggest chorus concerts of the year are tomarrow at school, and you can only skip it if you had a letter from your parents a week ago. otherwise, a lot of points will be taken off your chorus grade. and I want to go, because I love singing and stuff, but how can I get better in less than 24 hours??
thanks

Get a good night's sleep, stop thinking about it and eat something substantial, but healthy for you (not garbage like junk food and stuff).You'll do fine. You say you love singing so you MUST be good at it. There are two things you can do: 1) You can either sit around feeling sick and being miserable thinking about it or 2) you can get up and do something productive which would get your mind off of it. It's natural to get nervous before a big event, but you can't let it consume you and effect you in a negative way.